Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GI Anatomy > Microbiota of GI tract > Flashcards

Microbiota of GI tract Flashcards

1
Q

Why does transit time affect bacterial populations in different parts of the GI tract

A

Due to different bacterial growth rates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Transit time of food in the mouth

A

1 min max

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Transit time of food in the oesophagus

A

4-8 secs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Transit time of food in the stomach

A

2-4 hrs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Transit time of food in the LI

A

10 hrs - several days

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

As you go down the GI tract, there’s more…

A

Bacteria

Esp obligate anaerobes because less oxygen the further down you go

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are facultative anaerobes + where are they found + what pH they live in

A

Grow in presence and absence of oxygen

Found in the stomach, existing at pH 1.5 - 4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Name some facultative anaerobes

A

Lactobacillus

H.pylori

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are obligate anaerobes + where are they found + what pH they live in

A

Can’t grow in presence of oxygen

Found in the colon at pH 5.5 - 6.5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Name some obligate anaerobes

A

Bacteroides
Clostridium groups
Enterobacteraceae

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

pH of mouth

A

6.5 - 7.5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

pH of duodenum

A

7-8.5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Main function of gut microbes

A

Metabolise undigested dietary components, e.g. fibre which is not digested in stomach/SI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

3 ways gut microbes can defend against pathogens

A

Acting as a barrier - to prevent pathogen colonisation

Active competitive exclusion - commensal bacteria can produce active compounds to kill pathogens

pH inhibition - pathogens generally grow best at ph>6, proximal colon has pH 5.5 but distal colon pH 6.5

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

More risk of pathogen colonisation in proximal or distal colon + why

A

proximal colon has pH 5.5 but distal colon usually pH 6.5 so MORE RISK OF PATHOGEN COLONISATION IN DISTAL COLON as pathogens grow best at ph>6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Functions of bacteria in the GI tract (6)

A 
Metabolise undigested dietary components
Defend against pathogens
Produce essential metabolites, e.g. short chain fatty acids
Modify host secretions, e.g. bile
Develop immune system
Control host signalling
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Function of E. rectale & F. prausnitzii

A

Produce butyrate ( a SCFA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Function of megasphaera

A

Produce propionate ( a SCFA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Function of bactericides

A

Utilise acetate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Functions of bifidobacteria (2)

A

Utilise prebiotics

Produce lactate

21
Q

Functions of lactobacilli (2)

A

Produce lactic acid

Degrade mucin

22
Q

High bacterial diversity is a biomarker of what

A

Good health

23
Q

Products of microbial fermentation (5)

A 
Short chain fatty acids/ branched chain fatty acids
Phytochemicals
Gases - CO2, H2, CH4
Other metabolites
Minerals
24
Q

3 main short chain fatty acids from carbohydrate metabolism

A

Butyrate
Proprionate
Acetate

25
Q

Function of butyrate (a SCFA)

A

involved in epithelial cell growth

26
Q

Function of propionate

A

involved in gluconeogenesis

27
Q

Function of acetate

A

transported in blood to peripheral tissues, involved in lipogenesis

28
Q

Rate of butyrate:propionate:acetate

A

1:1:3

29
Q

Bacterial in proximal colon ferment more carbohydrate/protein while bacteria in distal colon ferment more carbohydrate/protein

A

Carbohydrate

Protein

30
Q

Dysbiosis of gut microbiotia disrupts what which leads to what

A

Disrupts homeostasis –> gut inflammation

31
Q

Dietary fibre improves what

A

Faecal bulking resulting in shorter transit time in colon

32
Q

Fermentation of fibre by bacteria leads to what

A

Release of additional phytochemicals
Maintains acidic pH - to resist pathogens
Increases commensal bacteria
Essential supply of SCFAs

33
Q

Babies have low or high bacterial diversity

A

Low

34
Q

Difference between causation and correlation with respect to microbes and disease

A

Microbial dysbiosis could be a cause of gut disease but it could also be the gut disease that’s causing microbial dysbiosis

35
Q

Name some infections/disease that are caused by microbial dysbiosis (i.e. usually these bacteria live asymptomatically) (4)

A

MRSA (Staph aureus) infection
Streptococcus throat infection
C. diff infection
Gastritis/ Gastric cancer- H.pylori

36
Q

Inflammation in IBD is most likely due to what in regards to microbiota and immune response

A

Dysregulated immune response to gut microbiota

37
Q

Evidence has shown that there’s reduced bacterial diversity in crohn’s or UC

A

Crohn’s

38
Q

In crohn’s there may be elevated levels of what type of bacteria

A

Enterobacteriaceae

39
Q

How do features of IBD itself have an impact on microbiota (4)

A

Antibiotic use - reduces bacterial diversity
Inflammation - decreases mucus barrier –> more oxygen exposure –> changes microbial composition
Diarrhoea - decreased transit time altering microbial composition
Diet - desire to eat less fibre –> changes microbial composition

40
Q

Effect of antibiotics on gut microbiota

A

Reduce bacterial diversity
-creates selection pressure (loss of diverse bacteria, left with just a few species) resulting in the increase and spread of a bacterial resistance

41
Q

Effect of broad spectrum antibiotics on bacteria

A

kill pathogenic bacteria AND kill many of the commensal, resident bacteria that may be important for health

42
Q

What are probiotics

A

live micro-organisms conferring health benefit when administered adequately, e.g. Bifidobacterium

43
Q

Frequent functions of probiotics (3)

A

Bioconversion
Antagonistic to pathogens
Stimulate immune system

44
Q

What are probiotics

A

substrate used by host bacteria (food for bacteria) conferring health benefit, e.g. garlic

45
Q

Probiotics can potentially be used to treat what disease

A

reduce incidence of C. diff associated diarrhoea

46
Q

How may prebiotics may be helpful in IBD

A

IBD to boost numbers of Faecalibacterium prausnitzii so enhancing production of anti-inflammatory protein and reducing effects of IBD

47
Q

Function of Faecalibacterium prausnitzii (F. prausnitzi)

A

production of anti-inflammatory protein

48
Q

Potential functions of prebiotics (4)

A

Improve gut function by increasing faecal bulk
Reduce risk of colon cancer by reducing DNA damage
Used in infant formula to increase bifidobacteria numbers
Increase calcium absorption

49
Q

Explain why FMT (faecal microbial transplantation) may be more effective in treating recurrent C. difficile infection than other GI diseases

A

Faecal sample from healthy donor transplanted and repopulates microbiota of colon, displacing C. diff and preventing re-infection

may not work in other GI diseases because success depends on whether any microbiota is present/absent
-In c. diff infection, majority of microbiota is destroyed which allows FMT to work

GI Anatomy (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions